Factors influencing the comparability of poverty estimates across household surveys

Figures & data

Table 1. Availability of income and expenditure information in the 1993–2012 South African household surveys: a summary

Survey	Year	Question asked?	Recall or diary method?	Data captured in bands or actual amounts?	Overall amount or aggregation of amounts from different sources?	Number of bands, if the data are captured in bands
Income
Census	1996 2001 2011	Yes	Recall	Bands	Overall	Between 12 and 14
CS	2007	Yes	Recall	Bands	Overall	12
IES	1995 2000 2005/06	Yes	Recall	Actual amounts	Aggregation	N/A
OHS	1995–99	Yes (1999 only)	Recall	Bands	Overall	8
LFS	2000–07	No	N/A
QLFS	2008–	No
GHS	2002–09	No
PSLSD	1993	Yes	Recall	Actual amounts	Aggregation	N/A
NIDS	2008, 2010, 2012	Yes	Recall	Actual amounts	Aggregation Overall	15
AMPS	1993–2012	Yes	Recall	Bands	Overall	Between 29 and 32
Expenditure
Census	1996 2001 2007 2011	No	N/A
IES	1995 2000 2005/06 2010/11	Yes	Recall in 1995 and 2000; recall and diary methods in 2005/06 and 2010/11	Actual amounts	Aggregation	N/A
OHS	1995–99	Yes (in 4 surveys)	Recall	1996–98: actual amounts 1999: bands	Overall	8 (1999)
LFS	2000–07	Yes (in 4 surveys)	Recall	Bands	Overall	8
QLFS	2008–	No	N/A
GHS	2002–12	Yes	Recall	Bands	Overall	Between 8 and 10
NIDS	2008, 2010, 2012	Yes	Recall	Actual amounts	Aggregation	N/A
AMPS	1993–2012	No	N/A

QLFS = Quarterly Labour Force Survey; N/A = Not applicable; CS = Community Survey

Figure 1. Total income and expenditure (Rand million, 2013 prices) of surveys that collected both income and expenditure.

Figure 2. Total income or expenditure (Rand million, 2013 prices) of selected surveys taking place in the same year.

Figure 3. Annual food and transport expenditure (Rand million, 2013 prices) in the IESs (STC approach).

Figure 4. Poverty headcount ratios in each survey, 1993–2012 (Poverty line: R665 per capita per month, 2013 prices).

Table 2. Poverty headcount ratios in NIDS (Poverty line: R665 per capita per month, 2013 prices), only including respondents reporting income (expenditure) in both the single estimate approach and the aggregation approach before imputations.

			Poverty headcount ratio
	Sample size	Number of households reporting income under both approaches	One-shot approach	Aggregation approach
Income
NIDS 2008	7 301	5 441	0.631	0.590
NIDS 2010	6 809	5 557	0.619	0.523
NIDS 2012	8 040	7 381	0.532	0.414
Expenditure
NIDS 2008	7 301	5 776	0.745	0.629
NIDS 2010	6 809	5 667	0.803	0.684
NIDS 2012	8 040	7 670	0.685	0.683

Table 3. Total income derived income by the aggregation approach/total income derived by the single estimate approach ratio, NIDS 2012.

Ratio category	Proportion of households in each ratio category (%)
[0; 0.2)	3.0
[0.2; 0.4)	3.6
[0.4; 0.6)	4.6
[0.6; 0.8)	6.8
[0.8; 1.0)	10.5
1	8.3
(1; 1.2)	18.1
[1.2; 1.4)	12.3
[1.4; 1.6)	8.0
[1.6; 1.8)	4.5
[1.8; 2)	3.7
[2+)	16.7
	100.0
< 1	28.5
= 1	8.3
> 1	63.3

Table 4. Poverty headcount ratios in IESs (Poverty line: R665 per capita per month, 2013 prices), if the interval method is applied.

	Poverty headcount ratio
IES 1995
Actual continuous income variable	0.434
Applying the OHS 1996 intervals	0.418
Applying the Census 1996 intervals	0.423
Applying the AMPS 1995 intervals	0.435
IES 2000
Actual continuous income variable	0.559
Applying the LFS 2001 intervals	0.552
Applying the Census 2001 intervals	0.558
Applying the AMPS 2000 intervals	0.547
IES 2005/06
Actual continuous income variable	0.488
Applying the GHS 2005 intervals	0.476
Applying the CS 2007 intervals	0.481
Applying the AMPS 2005 intervals	0.481
IES 2010/11
Actual continuous income variable	0.468
Applying the GHS 2010 intervals	0.449
Applying the Census 2011 intervals	0.420
Applying the AMPS 2010 intervals	0.469

Table A1. Number and width of monthly income and expenditure bands in selected surveys

Census 1996 income	Width	AMPS 2009 income	Width
None	N/A	R1–R499	500
R1–R200	200	R500–R599	100
R201–R500	300	R600–R699	100
R501–R1 000	500	R700–R799	100
R1 001–R1 500	500	R800–R899	100
R1 501–R2 500	1 000	R900–R999	100
R2 501–R3 500	1 000	R1 000–R1 099	100
R3 501–R4 500	1 000	R1 100–R1 199	100
R4 501–R6 000	1 500	R1 200–R1 399	200
R6 001–R8 000	2 000	R1 400–R1 599	200
R8 001–R11 000	3 000	R1 600–R1 999	400
R11 001–R16 000	5 000	R2 000–R2 499	500
R16 001–R30 000	14 000	R2 500–R2 999	500
R30 001 above	N/A	R3 000–R3 999	1 000
Census 2001, CS 2007 and Census 2011 – income		R4 000–R4 999	1 000
None	N/A	R5 000–R5 999	1 000
R1–R400	400	R6 000–R6 999	1 000
R401–R800	400	R7 000–R7 999	1 000
R801–R1 600	800	R8 000–R8 999	1 000
R1 601–R3 200	1 600	R9 000–R9 999	1 000
R3 201–R6 400	3 200	R10 000–R10 999	1 000
R6 401–R12 800	6 400	R11 000–R11 999	1 000
R12 801–R25 600	12 800	R12 000–R13 999	2 000
R25 601–R51 200	25 600	R14 000–R15 999	2 000
R51 201–R102 400	51 200	R16 000–R19 999	4 000
R102 401–R204 800	102 400	R20 000–R24 999	5 000
R204 801 or above	N/A	R25 000–R29 999	5 000
OHSs/LFSs/GHSs – expenditure		R30 000–R39 999	10 000
R0–R399^a	400	R40 000–R49 999	10 000
R400–R799	400	R50 000 or above	N/A
R800–R1 199	400
R1 200–R1 799	600
R1 800–R2 499	700
R2 500–R4 999	2 500
R5 000–R9 999	5 000
R10 000 or above	N/A

^aThe R0–R399 category has been broken down into three categories since GHS 2009, namely R0, R1–R199 and R200–399.

Table A2. Comparison of annual total income, expenditure and consumption in various surveys with annual total income in the national accounts in the same year and poverty headcount ratios in each survey (Poverty line: R665 per capita per month, 2013 prices), 1993–2012

Census / survey	Variable	Year	Amount (Rand million) (2013 prices)	As % of total income in the national accounts	Poverty headcount ratio
Census	Income – before SRMI	1996	608 419	50.5	0.606
		2001	756 903	52.5	0.670
		2011	1 582 899	71.3	0.560
	Income – after SRMI	1996	723 853	60.1	0.576
		2001	1 047 306	72.7	0.592
		2011	1 649 590	74.3	0.513
CS	Income – before SRMI	2007	1 300 457	68.9	0.529
	Income – after SRMI	2007	1 616 287	85.6	0.463
IES	Income – STC	1995	1 090 599	95.0	0.434
		2000	951 595	71.9	0.559
		2005/2006	1 362 043	72.2	0.488
		2010/2011	1 458 757	65.7	0.468
	Expenditure – STC	1995	1 073 448	93.5	0.447
		2000	948 072	71.7	0.564
		2005/2006	1 551 969	82.2	0.466
		2010/2011	1 406 229	63.4	0.437
	Income – COICOP	1995	1 023 576	89.2	0.462
		2000	912 800	69.0	0.572
		2005/2006	1 458 085	77.3	0.473
		2010/2011	1 743 965	78.6	0.406
	Consumption – COICOP	1995	756 064	65.9	0.502
		2000	669 475	47.8	0.601
		2005/2006	1 097 905	58.2	0.500
		2010/2011	1 388 603	62.6	0.404
OHS	Expenditure	1996	392 791	32.6	0.704
		1997	356 629	28.6	0.768
		1998	312 808	24.6	0.781
		1999	474 573	35.9	0.742
	Income	1999	1 254 855	94.9	0.617
LFS	Expenditure	2001	476 269	33.1	0.773
		2002	545 588	36.9	0.788
		2003	766 094	50.4	0.758
		2004	861 699	52.4	0.738
GHS	Expenditure	2002	438 868	29.7	0.778
		2003	594 820	39.1	0.762
		2004	552 625	33.6	0.733
		2005	618 595	34.9	0.710
		2006	646 148	34.2	0.731
		2007	674 350	33.9	0.695
		2008	953 570	46.7	0.712
		2009	1 252 163	61.1	0.675
		2010	1 538 740	72.7	0.654
		2011	1 672 952	75.4	0.619
		2012	1 893 180	81.7	0.568
PSLSD	Income	1993	691 179	65.3	0.596
	Expenditure	1993	615 039	58.1	0.566
NIDS	Income – aggregation approach	2008	1 297 138	63.1	0.471
		2010	1 729 288	81.7	0.448
		2012	1 486 459	64.2	0.365
	Income – single estimate approach	2008	791 843	38.5	0.631
		2010	1 260 274	59.5	0.618
		2012	1 530 747	66.1	0.532
	Expenditure – aggregation approach	2008	1 129 508	54.9	0.532
		2010	1 133 468	53.5	0.571
		2012	1 105 270	47.7	0.527
	Expenditure – single estimate approach	2008	442 427	21.5	0.744
		2010	349 857	16.5	0.791
		2012	700 969	30.3	0.686
AMPS	Income	1993	695 029	65.6	0.586
		1994	682 605	62.5	0.593
		1995	688 135	59.9	0.594
		1996	721 419	59.9	0.610
		1997	718 971	57.7	0.589
		1998	745 959	58.7	0.583
		1999	744 986	56.3	0.591
		2000	836 762	59.8	0.582
		2001	839 002	58.2	0.579
		2002	834 218	56.4	0.563
		2003	917 755	60.4	0.554
		2004	931 190	56.6	0.548
		2005	1 002 069	56.6	0.519
		2006	1 038 372	55.0	0.512
		2007	1 141 045	57.3	0.455
		2008	1 299 880	63.2	0.410
		2009	1 218 097	59.4	0.414